/*

 *

 * (C) 2013-24 - ntop.org

 *

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 3 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software Foundation,

 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

 *

 */

#ifndef _GENERIC_HASH_ENTRY_H_

#define _GENERIC_HASH_ENTRY_H_

#include "ntop_includes.h"

class Generichash;

/** @class GenericHashEntry

 *  @brief Base hash entry class.

 *  @details Defined the base hash entry class for ntopng.

 *

 *  This class handle entries placed in hash tables built

 *  with class GenericHash.

 *

 *  GenericHashEntry has a lifecycle which is written into

 *  the enum HashEntryState and is implemented as a finite states

 *  machine. States are:

 *

 *  - hash_entry_state_active. This state is the default one which

 *  is set as soon as the GenericHashEntry is instantiated.

 *

 *  - hash_entry_state_idle. This state is set by method purgeIdle

 *  in class GenericHash and is used to explicitly mark the entry

 *  as idle. NOTE that purgeIdle is always called inline, that is,

 *  in the thread which receives the incoming packets (or incoming

 *  flows). Once the entry has been marked as hash_entry_state_idle,

 *  the inline thread will not be able to fetch the entry again. Howevever,

 *  before deleting the entry, an extra transition is needed to make sure

 *  also a non-inline periodic thread has seen the entry.

 *

 *  - hash_entry_state_ready_to_be_purged. This state is set by

 *  non-inline periodic threads, generally from method updateStats,

 *  only after the inline thread has set state hash_entry_state_idle. This

 *  guarantees that also a non-inline thread has seen the entry before

 *  cleaning it up and freeing its memory. Once this state has been set,

 *  the inline-thread will perform the actual delete to free the memory.

 *

 *  The following diagram recaps the states transitions

 *

 *             ..new..

 *                |

 *                |

 *                v

 *      hash_entry_state_active

 *                |

 *                | [inline]

 *                v

 *      hash_entry_state_idle

 *                |

 *                | [non-inline]

 *                v

 *      hash_entry_state_ready_to_be_purged

 *                |

 *                |

 *                v

 *          ...deleted...

 *

 *  @ingroup MonitoringData

 *

 */

class GenericHashEntry {

 private:

  GenericHashEntry *hash_next; /**< Pointer of next hash entry.*/

  HashEntryState hash_entry_state;

  GenericHash *hash_table;

  /**

   * @brief Set one of the states of the hash entry in its lifecycle.

   *

   * @param s A state of the enum HashEntryState

   */

  void set_state(HashEntryState s);

 protected:

  std::atomic<int32_t> num_uses;

  time_t first_seen;       /**< Time of first seen. */

  time_t last_seen;        /**< Time of last seen. */

  NetworkInterface *iface; /**< Pointer of network interface. */

 public:

  /**

   * @brief A Constructor

   * @details Creating a new GenericHashEntry.

   *

   * @param _iface Network interface pointer for the new hash.

   * @return A new Instance of GenericHashEntry.

   */

  GenericHashEntry(NetworkInterface *_iface);

  /**

   * @brief A destructor.

   * @details Virtual method.

   *

   * @return Delete the instance.

   */

  virtual ~GenericHashEntry();

  /**

   * @brief Get the first seen time.

   * @details Inline method.

   *

   * @return Time of first seen.

   */

  inline time_t get_first_seen() const { return (first_seen); };

  /**

   * @brief Get the last seen time.

   * @details Inline method.

   *

   * @return Time of last seen.

   */

  inline time_t get_last_seen() const { return (last_seen); };

  /**

   * @brief Get the next hash entry.

   * @details Inline method.

   *

   * @return Return the next hash entry.

   */

  inline GenericHashEntry *next() { return (hash_next); };

  /**

   * @brief Set a pointer to the hash table this entry

   * hash been added to

   */

  void set_hash_table(GenericHash *gh) { hash_table = gh; };

  inline GenericHash *get_hash_table() { return (hash_table); };

  /**

   * @brief Set and id to uniquely identify this

   * hash entry into the hash table (class GenericHash)

   * it belongs to.

   */

  virtual void set_hash_entry_id(u_int32_t hash_entry_id){};

  /**

   * @brief Set the next hash entry.

   * @details Inline method.

   *

   * @param n Hash entry to set as next hash entry.

   */

  inline void set_next(GenericHashEntry *n) { hash_next = n; };

  /**

   * @brief Set the hash entry state to idle. Must be called inline

   * with packets/flows processing.

   *

   */

  virtual void set_hash_entry_state_idle() {

    set_state(hash_entry_state_idle);

  };

  /**

   * @brief Set the hash entry state to active

   */

  inline void set_hash_entry_state_active() {

    set_state(hash_entry_state_active);

  };

  /**

   * @brief Set the hash entry state to not yet detected (nDPI)

   */

  inline void set_hash_entry_state_flow_notyetdetected() {

    set_state(hash_entry_state_flow_notyetdetected);

  };

  /**

   * @brief Set the hash entry state to protocol detected (nDPI).

   * Note that unknown (protocol) is a valid protocol

   */

  inline void set_hash_entry_state_flow_protocoldetected() {

    set_state(hash_entry_state_flow_protocoldetected);

  };

  /**

   * @brief Set the hash entry state to allocated

   */

  inline void set_hash_entry_state_allocated() {

    /*

      We don't check anything here as it's used by flows to step back

      to the initial state

    */

    hash_entry_state = hash_entry_state_allocated;

  };

  /**

   * @brief Determine whether this entry is ready for the transition to the idle

   * state

   *

   */

  virtual bool is_hash_entry_state_idle_transition_ready() {

    return ((getUses() == 0) && is_active_entry_now_idle(MAX_HASH_ENTRY_IDLE));

  }

  /**

   * @brief Determine whether this active entry can be considered idle

   *

   */

  virtual bool is_active_entry_now_idle(u_int max_idleness) const;

  /**

   * @brief Function in charge of updating periodic entry stats (e.g., its

   * throughput or L7 traffic)

   *

   * @param user_date A pointer to user submitted data potentially necessary for

   * the update

   * @param quick Only perform minimal operations

   *

   */

  virtual void periodic_stats_update(const struct timeval *tv);

  inline HashEntryState get_state() const { return (hash_entry_state); }

  void updateSeen();

  void updateSeen(time_t _last_seen);

  bool equal(GenericHashEntry *b) { return ((this == b) ? true : false); };

  inline NetworkInterface *getInterface() { return (iface); };

  inline bool idle() const          { return (get_state() > hash_entry_state_active); }

  virtual void housekeep(time_t t)  { return; };

  inline u_int get_duration() const { return ((u_int)((1 + last_seen) - first_seen)); };

  virtual u_int32_t key()           { return (0); };

  virtual char *get_string_key(char *buf, u_int buf_len) const { buf[0] = '\0'; return (buf); };

  void incUses()                    { num_uses++; }

  void decUses()                    { num_uses--; }

  int32_t getUses() const           { return (num_uses); }

  virtual void getJSONObject(json_object *obj, DetailsLevel details_level);

};

#endif /* _GENERIC_HASH_ENTRY_H_ */